1. Field of the Invention
The present invention relates to a dead lock preventing method for a data base system, which can be used in the field of data searching control in, e.g., bank transactions, securities exchange, and medical examination facility and, more particularly, to a dead lock preventing method for a data base system, which can reliably prevent a dead lock that may be caused when a data base employed at one of a plurality of work stations (WS) arranged on a transmission route of a LAN (Local Area Network) is accessed by an arbitrary work station.
2. Description of the Related Art
In a distributed data-base-management-system (D-DBMS) in which a plurality of work stations (to be referred to as CPUs hereinafter) are distributed in a LAN and each CPU (i.e., a WS) independently has a data base, a plurality of data bases must be organically linked to each other to effectively utilize the data bases of the entire system. For this reason, serialization control is conventionally widely adopted to assure the same result of file updating between CPUs of WSs when an arbitrary CPU (WS) accesses a data base file employed in another CPU (WS) in order to perform data searching.
In addition, a prior art invention relevant to the present invention is disclosed in Published Unexamined European Patent Application No. 0278312. The following items will be described to explain one of typical conventional techniques.
(1) Serializability in file updating.
(2) General lock models for realizing the serialization control.
(3) A 2-phase lock as one of the lock models.
(4) Occurrence of a dead lock caused by the 2-phase lock.
(5) A time stamp method for eliminating the occurrence of a dead lock.